U.S. patent number 8,978,512 [Application Number 12/923,310] was granted by the patent office on 2015-03-17 for operating pedal and overlapping welding method.
This patent grant is currently assigned to Toyoda Iron Works Co., Ltd.. The grantee listed for this patent is Yoshiro Himetani, Nobuyuki Kawahara. Invention is credited to Yoshiro Himetani, Nobuyuki Kawahara.
United States Patent |
8,978,512 |
Himetani , et al. |
March 17, 2015 |
Operating pedal and overlapping welding method
Abstract
An operating pedal includes a joining portion at which a first
member and a second member whose thickness is smaller than a
thickness of the first member are overlapped with each other, and
welded to each other along an end edge of the second member, a step
portion being provided in the first member along the end edge of
the second member by recessing a protruding portion that outwardly
protrudes from the end edge so that the protruding portion is drawn
back from the second member; and the first member and the second
member being welded to each other at a portion extending from the
end edge of the second member to the step portion of the first
member.
Inventors: |
Himetani; Yoshiro (Toyota,
JP), Kawahara; Nobuyuki (Toyota, JP) |
Applicant: |
Name |
City |
State |
Country |
Type |
Himetani; Yoshiro
Kawahara; Nobuyuki |
Toyota
Toyota |
N/A
N/A |
JP
JP |
|
|
Assignee: |
Toyoda Iron Works Co., Ltd.
(Toyota-shi, Aichi-ken, JP)
|
Family
ID: |
43383478 |
Appl.
No.: |
12/923,310 |
Filed: |
September 14, 2010 |
Prior Publication Data
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|
Document
Identifier |
Publication Date |
|
US 20110094330 A1 |
Apr 28, 2011 |
|
Foreign Application Priority Data
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|
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|
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Sep 17, 2009 [JP] |
|
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2009-216272 |
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Current U.S.
Class: |
74/512; 74/513;
219/137R; 228/101; 74/560; 74/514 |
Current CPC
Class: |
B60T
7/06 (20130101); G05G 1/506 (20130101); Y10T
74/20528 (20150115); Y10T 74/2054 (20150115); Y10T
74/20534 (20150115); Y10T 74/20888 (20150115) |
Current International
Class: |
G05G
1/44 (20080401); G05G 1/30 (20080401) |
Field of
Search: |
;228/101 ;74/512-514,560
;219/137R |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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4335295 |
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Apr 1994 |
|
DE |
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2821684 |
|
Sep 2002 |
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FR |
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616981 |
|
Jan 1949 |
|
GB |
|
39-24920 |
|
Aug 1964 |
|
JP |
|
3-81479 |
|
Aug 1991 |
|
JP |
|
11-58039 |
|
Mar 1999 |
|
JP |
|
2007-122610 |
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May 2007 |
|
JP |
|
Other References
Machine Translation of JP 2007-122610, Yoshihiro et al., May 17,
2007. cited by examiner .
USPTO Translation of JP 3-81479, Sugino et al., Aug. 1991. cited by
examiner .
Abstract of FR 2821684, Denis, Sep. 2002. cited by examiner .
English Abstract of DE 4335295 A1, Douglas, Apr. 1994. cited by
examiner .
Office Action for JP Appl. No. 2009-216272 dated Jul. 31, 2012.
cited by applicant .
Office Action for Chinese Appl. No. 201010287338.1 dated Mar. 5,
2013. cited by applicant.
|
Primary Examiner: Luong; Vinh
Attorney, Agent or Firm: Finnegan, Henderson, Farabow,
Garrett & Dunner, LLP
Claims
What is claimed is:
1. An operating pedal including a joining portion at which a first
member and a second member whose thickness is smaller than a
thickness of the first member are overlapped with each other, and
welded to each other along an end edge of the second member, a step
portion being provided in the first member along the end edge of
the second member, the step portion recessing a protruding portion
that protrudes in a direction away from the end edge and decreasing
a thickness of the entire protruding portion smaller than other
portions of the first member so that the protruding portion is
drawn back from the second member, and the step portion being
formed to extend in a direction substantially perpendicular to the
direction in which the protruding portion protrudes; and the first
member and the second member being welded to each other only at a
portion extending from the end edge of the second member to the
step portion of the first member.
2. The operating pedal according to claim 1, wherein the second
member is a pedal arm which is made of a sheet material and has a
hollow structure, and in which a boss attachment cylindrical
portion with a cylindrical shape is provided to outwardly protrude;
the first member is a boss with a cylindrical shape, which is
disposed to extend through the boss attachment cylindrical portion,
and integrally welded to the boss attachment cylindrical portion,
and of which the operating pedal is supported to be pivotable
around a center line; and an inner diameter of the boss is constant
over an entire length of the boss, the protruding portion is an end
portion in an axial direction, which outwardly protrudes from the
boss attachment cylindrical portion, and the step portion is
provided by decreasing an outer diameter of the end portion.
3. An overlapping welding method in which a first member and a
second member whose thickness is smaller than a thickness of the
first member are overlapped with each other, and welded to each
other along an end edge of the second member, wherein a step
portion is provided in the first member along the end edge of the
second member, the step portion recesses a protruding portion that
protrudes in a direction away from the end edge and decreases a
thickness of the entire protruding portion smaller than other
portions of the first member so that the protruding portion is
drawn back from the second member, and the step portion is formed
to extend in a direction substantially perpendicular to the
direction in which the protruding portion protrudes; and the first
member and the second member are welded to each other at only a
portion extending from the end edge of the second member to the
step portion of the first member.
Description
INCORPORATION BY REFERENCE
The disclosure of Japanese Patent Application No. 2009-216272 filed
on Sep. 17, 2009 including the specification, drawings and abstract
is incorporated herein by reference in its entirety.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to an operating pedal, and particularly to
improvement of an operating pedal that includes a joining portion
at which two members are overlapped with each other and welded to
each other.
2. Description of the Related Art
An operating pedal, in which a boss with a cylindrical shape is
disposed to extend through a pedal arm, and integrally welded to
the pedal arm, is known. The pedal arm is made of a thin plate and
has a hollow structure. The operating pedal is supported to be
pivotable around a center line of the boss. A vehicle operating
pedal described in Japanese Patent Application Publication No.
2007-122610 (JP-A-2007-122610) is an example of the operating
pedal. In the vehicle operating pedal, a pedal arm, which is made
of a thin plate and has a hollow structure, is formed by welding
outer peripheral portions of paired half bodies to each other. Each
of the paired half bodies has a shape obtained by dividing the
pedal arm in a vehicle width direction. A boss is disposed to
extend through boss attachment cylindrical portions provided in the
half bodies by operating a burring-hole forming process. The boss
is integrally fixed to the boss attachment cylindrical
portions.
FIG. 6A is a sectional view explaining an example of a joining
portion at which a pedal arm 14 and a boss 100 are joined to each
other in a conventional operating pedal. FIG. 6A is a diagram
corresponding to a section taken along a line IIIA-IIIA in FIG. 2.
The pedal arm 14 is formed by welding outer peripheral portions of
paired half bodies 32 and 34 to each other. Each of the paired half
bodies 32 and 34 has a shape obtained by dividing the pedal arm 14
in the vehicle width direction. Thus, the pedal arm 14 is made of a
thin plate and has a hollow structure. Outer peripheral flanges 32f
and 34f are provided in the half bodies 32 and 34, respectively.
While the outer peripheral flanges 32f and 34f are overlapped with
each other, the outer peripheral flanges 32f and 34f are integrally
welded to each other, for example, by arc welding. A first joining
portion W1 (a blacked-out region) is a joining portion at which the
outer peripheral flanges 32f and 34f are joined to each other. Boss
attachment cylindrical portions 32g and 34g with a cylindrical
shape are provided in the half bodies 32 and 34, respectively, by
operating a burring-hole forming process and the like. The boss 100
with a cylindrical shape is disposed to extend through the boss
attachment cylindrical portions 32g and 34g. The boss 100 is
integrally fixed to the boss attachment cylindrical portions 32g
and 34g, for example, by arc welding or laser welding. Second
joining portions W2 (mesh regions) are joining portions at which
the boss attachment cylindrical portions 32g and 34g and the boss
100 are joined to each other. The boss attachment cylindrical
portions 32g and 34g and the boss 100 are discontinuously joined to
each other at the joining portions located at predetermined
intervals around a center line O.
However, when the boss 100 and the boss attachment cylindrical
portions 32g and 34g are welded to each other, for example, by
plasma arc welding while the boss 100 is fitted in the boss
attachment cylindrical portions 32g and 34g, and outer peripheral
surfaces of the boss 100 are overlapped with the boss attachment
cylindrical portions 32g and 34g, because the thickness (plate
thickness) of each of the boss attachment cylindrical portions 32g
and 34g is smaller than the thickness of the boss 100, heat input
to the boss 100 tends to be insufficient, and heat input to the
boss attachment cylindrical portions 32g and 34g tends to be
excessive. Thus, joining failure is easily to occur. That is, the
amount of heat input to the boss 100 needs to be larger than the
amount of heat input to the boss attachment cylindrical portions
32g and 34g, in order to generate a molten pool, and as a result,
there is a problem that, for example, a throat of weld is decreased
in thickness due to a decrease in the amount of molten metal in the
boss attachment cylindrical portions 32g and 34g, and expansion of
a melting width (expansion toward a right side in FIG. 6B. FIG. 6B
is a sectional view showing an enlarged VIIB portion in FIG. 6A,
which is rotated by 90.degree. in a counterclockwise direction. The
thickness (throat thickness) D of the joining portion at a position
near a border between the second joining portion W2 and the boss
attachment cylindrical portion 32g of the half body 32 becomes
small, and therefore, there is a possibility that joint strength
may be deteriorated. In addition, because the amount of heat input
to the boss 100 becomes large, there is a possibility that heat
strain may occur in the boss 100, and the inner diameter of the
boss 100 may be changed, and thus, performance of supporting the
boss 100 using the support shaft may be deteriorated.
The problems occur not only in the joining portion between the
pedal arm and the boss, but also in other joining portions, for
example, a joining portion between the pedal arm and the pedal
sheet.
SUMMARY OF THE INVENTION
The invention has been made under such circumstances and an object
of the invention is to suppress occurrence of joining failure and
heat strain due to imbalance in the amount of input heat when two
members constituting an operating pedal are overlapped with each
other and welded to each other.
The object indicated above is achieved in the first aspect of the
present invention, which provides an operating pedal including a
joining portion at which a first member and a second member whose
thickness is smaller than a thickness of the first member are
overlapped with each other, and welded to each other along an end
edge of the second member, wherein (a) a step portion is provided
in the first member along the end edge of the second member by
recessing a protruding portion that outwardly protrudes from the
end edge so that the protruding portion is drawn back from the
second member; and (b) the first member and the second member are
welded to each other at a portion extending from the end edge of
the second member to the step portion of the first member.
The object indicated above is achieved in the second aspect of the
present invention, which provides the operating pedal according to
the first aspect of the present invention, wherein (a) the second
member is a pedal arm which is made of a thin plate and has a
hollow structure, and in which a boss attachment cylindrical
portion with a cylindrical shape is provided to outwardly protrude;
(b) the first member is a boss with a cylindrical shape, which is
disposed to extend through the boss attachment cylindrical portion,
and integrally welded to the boss attachment cylindrical portion,
and of which the operating pedal is supported to be pivotable
around a center line; and (c) an inner diameter of the boss is
constant over an entire length of the boss, the protruding portion
is an end portion in an axial direction, which outwardly protrudes
from the boss attachment cylindrical portion, and the step portion
is provided by decreasing an outer diameter of the end portion.
The object indicated above is achieved in the third aspect of the
present invention, which provides an overlapping welding method in
which a first member and a second member whose thickness is smaller
than a thickness of the first member are overlapped with each
other, and welded to each other along an end edge of the second
member, wherein (a) a step portion is provided in the first member
along the end edge of the second member by recessing a protruding
portion that outwardly protrudes from the end edge so that the
protruding portion is drawn back from the second member; and (b)
the first member and the second member are welded to each other at
a portion extending from the end edge of the second member to the
step portion of the first member.
In the operating pedal, because the step portion is provided in the
first member along the end edge of the second member, it is
possible to efficiently and intensively input heat to the portion
extending from the end edge of the second member to the step
portion of the first member. Thus, it is possible to ensure a
predetermined throat thickness, thereby improving joint strength,
while suppressing occurrence of heat strain. Further, because heat
is appropriately released from the protruding portion that is
provided to be continuous with the step portion, expansion of a
melted area in the members is prevented. This also suppresses a
decrease in the throat thickness, and heat strain in the first
member. In the overlapping welding method according to the third
invention as well, it is possible to obtain the substantially same
advantageous effects.
According to the second aspect of the present invention, the boss
with a cylindrical shape is disposed to extend through the pedal
arm that is made of a thin plate, and that has a hollow structure,
and the boss is integrally welded to the pedal arm. The inner
diameter of the boss is constant over an entire length of the boss,
and the step portion is provided by decreasing the outer diameter
of the end portion in the axial direction, which outwardly
protrudes from the boss attachment cylindrical portion of the pedal
arm. It is possible to efficiently and intensively input heat to
the portion extending from the end edge of the boss attachment
cylindrical portion to the step portion of the boss. In addition,
because heat is released from the end portion of the boss that is
provided to be continuous with the step portion, it is possible to
ensure the predetermined throat thickness, thereby improving the
joint strength, while suppressing occurrence of heat strain.
BRIEF DESCRIPTION OF THE DRAWINGS
The foregoing and further objects, features and advantages of the
invention will become apparent from the following description of
example embodiments with reference to the accompanying drawings,
wherein like numerals are used to represent like elements and
wherein:
FIGS. 1A and 1B are diagrams each showing a brake pedal for a
vehicle, to which the invention is applied, FIG. 1A is a left side
view, and FIG. 1B is a front view;
FIG. 2 is a diagram showing an enlarged support portion at an upper
end portion, which is supported by a support shaft in FIG. 1A;
FIGS. 3A and 3B are diagrams each explaining a joining structure in
which a pedal arm and a boss are joined to each other in the brake
pedal in FIGS. 1A and 1B, FIG. 3A is an enlarged view of a section
taken along a line IIIA-IIIA in FIG. 2, and FIG. 3B is a sectional
view showing an enlarged IIIB portion in FIG. 3A, which is rotated
by 90.degree. in a counterclockwise direction;
FIG. 4 is a sectional view showing a state before welding is
operated at a second joining portion W2 in FIG. 3B;
FIGS. 5A and 5B, which are diagrams explaining other embodiments of
the invention, are left side views corresponding to FIG. 2; and
FIGS. 6A and 6B are diagrams each of which explains an example of a
conventional joining structure in which a pedal arm and a boss are
joined to each other, and which correspond to FIGS. 3A and 3B,
respectively, FIG. 6A is an enlarged view corresponding to a
section taken along the line IIIA-IIIA in FIG. 2, and FIG. 6B is a
sectional view showing an enlarged VIIB portion in FIG. 6A, which
is rotated by 90.degree. in the counterclockwise direction.
DETAILED DESCRIPTION OF EMBODIMENTS
The invention is appropriately applied to a vehicle operating
pedal, for example, a brake pedal for a service brake or a parking
brake, and an accelerator pedal. However, the invention can be
applied to an operating pedal other than the vehicle operating
pedal. The second invention relates to a case where a boss with a
cylindrical shape is joined to a pedal arm that is made of a thin
plate and has a hollow structure, by welding. For example, the
invention can be applied to a case where a pedal sheet is welded to
a sheet attachment plate portion provided at a lower end portion of
the pedal arm, and the thickness of the pedal sheet is larger than
the thickness of the sheet attachment plate portion. The invention
can be also applied to an operating pedal that includes a pedal arm
other than the pedal arm with a hollow structure. Further, the
invention can be applied to a case where a member other than the
boss and the pedal sheet is integrally welded to the pedal arm.
Thus, the invention can be applied to various operating pedals each
of which is formed by welding two members constituting the
operating pedal.
It is appropriate to employ a welding method in which welding is
operated by melting only base materials (a first material and a
second material) without using a welding material, as a welding
method for welding the first member and the second member to each
other. For example, plasma arc welding and TIG welding that are
non-consumable electrode welding methods, laser welding, and
electron beam welding may be employed. It is preferable that a
length T of a step portion of the first member and a thickness "t"
of the second member should satisfy a relation, 2.0t.ltoreq.T, to
ensure a predetermined throat thickness, thereby improving joint
strength while suppressing occurrence of heat strain. Also, the
length T of the step portion is preferably equal to or smaller than
3.0t, and more preferably equal to or smaller than 2.5t so that
expansion of a melted area in the members, and heat strain are
prevented by releasing heat from a protruding portion.
It is preferable that the step portion should be formed to extend
in a direction substantially perpendicular to an end edge of the
second member (i.e., a direction substantially perpendicular to a
direction in which the protruding portion protrudes). However, the
step portion may be inclined from the direction perpendicular to
the end edge, for example, by an angle equal to or smaller than
approximately 30.degree.. In this case, the inclination angle is
appropriately set to be in a range in which predetermined welding
quality is obtained. The step portion is formed, for example, by
decreasing the plate thickness (thickness) of the protruding
portion as in the second invention. However, the step portion may
be formed by operating a bending process, a drawing process, a
forging process, or the like to deform the first member so that the
thickness of step portion is substantially constant, and has a
crank-shaped section.
The pedal arm, which is made of a thin plate and has a hollow
structure, may have various configurations. For example, the pedal
arm may be formed by bending one steel plate or the like into a
cylindrical shape, or may be formed using a square pipe or the
like. The pedal arm may be formed by integrally joining paired half
bodies that are made of steel plates or the like, and have
hat-shaped sections or the like, by welding or the like, while the
half bodies face each other, and flanges at outer peripheral
portions of the half bodies are overlapped with each other so that
the flanges are in contact with each other. The operating pedal
with a hollow structure need not necessarily be pouched, that is,
the entire periphery of the operating pedal need not necessarily be
closed. A portion of the periphery of the operating pedal may be
open.
A boss attachment cylindrical portion with a cylindrical shape in
the second invention is provided, for example, by operating a
burring-hole forming process. The step portion formed at an end
portion of the boss is provided, for example, by operating a
cutting process on an outer peripheral surface thereof, or
operating a forging process. However, it is possible to employ
other processing methods to form the step portion. In the second
invention, the inner diameter of the boss is constant, and only the
outer diameter of the boss is changed. However, for example, it is
possible to change the inner diameter as well so that the thickness
is substantially constant.
Embodiment
Hereinafter, an embodiment of the invention will be described in
detail with reference to the drawings. FIGS. 1A and 1B are diagrams
each showing a brake pedal 10 for a service brake of a vehicle.
FIG. 1A is a left side view, and FIG. 1B is a front view. FIG. 2 is
an enlarged view of an upper end portion in FIG. 1A. FIGS. 3A and
3B are diagrams each explaining a joining structure in which a
pedal arm 14 and a boss 16 are joined to each other in the brake
pedal 10, FIG. 3A is an enlarged view of a section taken along a
line IIIA-IIIA in FIG. 2, and FIG. 3B is a sectional view showing
an enlarged IIIB portion in FIG. 3A, which is rotated by 90.degree.
in a counterclockwise direction. The brake pedal 10 corresponds to
an operating pedal according to the embodiment of the invention.
The brake pedal 10 includes the pedal arm 14 as a main component.
The boss 16 with a cylindrical shape, which is integrally fixed to
the upper end portion of the pedal arm 14, is concentrically fitted
to a support shaft 12. Thus, the operating pedal 10 is supported to
be pivotable around a center line O of the boss 16. The center line
O of the boss 16 substantially coincides with a shaft center of the
support shaft 12.
A pedal sheet 18 in the form of a plate is integrally fixed to a
lower end of the pedal arm 14. When the pedal sheet 18 is depressed
by a driver, the brake pedal 10 is pivoted around the support shaft
12 in a clockwise direction in FIG. 1A. A push rod 22 of a brake
master cylinder is connected to the brake pedal 10 through a
crevice 24 so that the push rod 22 is relatively pivotable around
an axis of a connection pin 20 that is substantially parallel to
the support shaft 12. When the push rod 22 is mechanically pressed
toward a left side in the figure due to the pivoting of the brake
pedal 10, a brake hydraulic pressure is generated in accordance
with depressing force of the brake pedal 10. The push rod 22 is
urged to protrude from the brake master cylinder. When the pedal
sheet 18, which has been depressed, is released, the brake pedal 10
is returned, that is, pivoted around the support shaft 16 in the
counterclockwise direction due to the urging force, and thus, the
brake pedal 10 is maintained in an original position shown in FIG.
1A.
The pedal arm 14 is made of a thin plate and has a hollow
structure. The pedal arm 14 is constituted by paired half bodies 32
and 34 each of which has a shape obtained by dividing the pedal arm
14 in half in a width direction of the vehicle, that is, a
right-left direction in FIG. 1B. Each of the half bodies 32 and 34
is formed by pressing and bending a steel plate, and has a
substantially hat-shaped section. While open sides of the
hat-shaped sections of the half bodies 32 and 34 face each other,
and outer peripheral flanges 32f and 34f are overlapped with each
other so that the outer peripheral flanges 32f and 34f are in close
contact with each other, outer end edges of the outer peripheral
flanges 32f and 34f, that is, end edges extending in a front-rear
direction and a top-bottom direction of the vehicle are integrally
welded to each other by plasma arc welding that is a non-consumable
electrode welding method. The outer peripheral flanges 32f and 34f
are provided around open portions of the half bodies 32 and 34 to
extend outwardly, and parallel to each other. In FIG. 3A, a first
joining portion W1 (a blacked-out region) indicates a joining
portion at which the outer peripheral flanges 32f and 34f are
joined to each other. The outer peripheral flanges 32f and 34f are
provided in the pedal arm 14 excluding an upper end front portion
located on a left side of the boss 16 in FIG. 3A, and a lower end
rear portion to which the pedal sheet 18 is fixed, and the outer
peripheral flanges 32f and 34f are integrally welded to each
other.
Boss attachment cylindrical portions 32g and 34g are provided at
upper end portions of the paired half bodies 32 and 34, to which
the boss 16 is fixed, as shown in FIG. 3A. Each of the boss
attachment cylindrical portions 32g and 34g with a cylindrical
shape is provided to outwardly protrude by operating a burring-hole
forming process or the like. The inner diameter of each of the boss
attachment cylindrical portions 32g and 34g is substantially equal
to the outer diameter of the boss 16. The boss 16 is fitted in the
boss attachment cylindrical portions 32g and 34g to extend through
the boss attachment cylindrical portions 32g and 34g. While each of
end portions 40a and 40b in the axial direction protrudes by a
predetermined length, the boss 16 and the boss attachment
cylindrical portions 32g and 34g are integrally welded to each
other at fitting portions of the boss attachment cylindrical
portions 32g and 34g, that is, at portions at which the boss 16 and
the boss attachment cylindrical portions 32g and 34g are overlapped
with each other, by plasma arc welding that is the non-consumable
electrode welding method, as well as at the first joining portion
W1. The thickness of the boss 16 is sufficiently larger than the
thickness (plate thickness) of each of the boss attachment
cylindrical portions 32g and 34g. The inner diameter of the boss 16
is constant over an entire length thereof. However, the outer
diameter of each of the end portions 40a and 40b in the axial
direction, which outwardly protrude from the boss attachment
cylindrical portions 32g and 34g, respectively, is decreased, for
example, by operating a cutting process on outer peripheries of the
end portions 40a and 40b, or operating a forging process. Thus,
step portions 42a and 42b are provided along end edges of the boss
attachment cylindrical portions 32g and 34g, respectively, at the
substantially same positions as the positions of the end edges of
the boss attachment cylindrical portions 32g and 34g, respectively.
The step portions 42a and 42b extend in a direction substantially
perpendicular to the end edges. The plasma arc welding is operated
along L-shaped corners that extend from outer peripheral surfaces
of the end edges of the boss attachment cylindrical portions 32g
and 34g to the step portions 42a and 42b, respectively. In FIG. 2
and FIGS. 3A and 3B, second joining portions W2 (mesh regions)
indicate joining portions at which the boss attachment cylindrical
portions 32g and 34g are joined to the boss 16. As evident from
FIG. 2, in the embodiment, the welding is operated at predetermined
four portions located at equal angle intervals around the center
line O. Each of the predetermined four portions extends in an angle
range of approximately 45.degree.. The boss 16 corresponds to the
first member. The pedal arm 14 corresponds to the second member.
The end portions 40a and 40b of the boss correspond to the
protruding portions.
FIG. 4 shows the same portion as the portion shown in FIG. 3B in a
state before the plasma arc welding is operated. A welding torch 44
for plasma arc welding is moved along the L-shaped corner extending
from the outer peripheral surface of the end edge of the boss
attachment cylindrical portion 32g to the step portion 42a of the
boss 16 to input heat to a target joining portion IVW shown by a
chain line. In this case, because the step portion 42a is provided,
it is possible to efficiently and intensively input heat to the
target joining portion IVW in the boss attachment cylindrical
portion 32g and the boss 16. Thus, it is possible to ensure a
predetermined throat thickness, thereby improving joint strength,
while suppressing occurrence of heat strain and expansion of a
melted area in the members. In the embodiment, a throat thickness D
(refer to FIG. 3B) is substantially equal to an original thickness
"t" of the boss attachment cylindrical portion 32g. Thus, it is
preferable that the length T of the step portion 42a should be set
to be equal to or larger than two times the thickness "t" of the
boss attachment cylindrical portion 32g, and equal to or smaller
than the three times the thickness "t" of the boss attachment
cylindrical portion 32g (i.e., the length T and the thickness "t"
should satisfy the relation: 2.0t.ltoreq.T.ltoreq.3.0t), in order
to ensure the predetermined throat thickness D while suppressing
occurrence of heat strain and expansion of the melted area in the
members.
Thus, in the brake pedal 10 according to the embodiment, the boss
16 with a cylindrical shape is disposed to extend through the pedal
arm 14 that is made of a thin plate, and that has a hollow
structure, and the boss 16 is integrally welded to the pedal arm
14. The step portions 42a and 42b are provided by decreasing the
outer diameters of the end portions 40a and 40b in the axial
direction, which outwardly protrude from the boss attachment
cylindrical portions 32g and 34g of the pedal arm 14, respectively.
The plasma arc welding is operated on the L-shaped corner portions
that extend from the outer peripheral surfaces of the end edges of
the boss attachment cylindrical portions 32g and 34g to the step
portions 42a and 42b, respectively. Therefore, it is possible to
efficiently and intensively input heat to the target joining
portions IVW in the boss attachment cylindrical portions 32g and
34g and the boss 16. Thus, it is possible to ensure the
predetermined throat thickness D, thereby improving the joint
strength, while suppressing occurrence of heat strain. Further, the
end portions 40a and 40b are provided integrally with the step
portions 42a and 42b, respectively, in a manner such that the end
portions 40a and 40b are continuous with the step portions 42a and
42b, respectively, and each of the end portions 40a and 40b
protrudes by the predetermined length. Thus, heat is appropriately
released from the end portions 40a and 40b. Therefore, it is
possible to prevent expansion of the melted area in the members.
This also suppresses a decrease in the throat thickness D, and heat
strain in an inner peripheral surface of the boss 16.
In the above-described embodiment, the pedal arm 14 and the boss 16
are welded to each other at the four portions around the center
line O. Each of the four portions extends in the angle range of
approximately 45.degree.. However, as shown in FIG. 5A, the pedal
arm 14 and the boss 16 may be welded to each other at two portions
that are symmetrically located with respect to the center line O,
and each of the two portions may extend in the angle range of
approximately 90.degree.. Further, as shown in FIG. 5B, the pedal
arm 14 and the boss 16 can be welded to each other over an entire
circumference around the center line O.
Although the embodiments of the invention have been described in
detail with reference to the drawings, the embodiments are merely
examples, and the invention can be implemented in various forms
obtained by altering or modifying the embodiments based on the
knowledge of those skilled in the art.
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